Structural and mechanistic characterization of a genomically discovered lipase SHSL for enhanced diacylglycerol enrichment in Camellia oleifera oil

SHSL was mined from Streptomyces sp. CL10 and expressed as an alkaline lipase. • LC-MS showed TAG depletion, DAG enrichment, and low MAG in Camellia oleifera oil. • Triolein, diolein, and monoolein were used to model acylglycerol recognition. • Docking showed substrate-dependent positioning in the SHSL catalytic groove. • MD revealed triolein-favored catalytic geometry for TAG-to-DAG redistribution. Enzymatic modification of woody plant oils can improve their functional glyceride composition and expand their value in lipid-based applications. In this study, a hormone-sensitive lipase, SHSL, was identified from Streptomyces sp. CL10 through genome mining and domain/motif-based screening. Recombinant SHSL showed alkaline lipase activity, with an optimal temperature of 45°C and an optimal pH of 8.0. LC-MS analysis showed that SHSL treatment reshaped the detected glyceride pool of Camellia oleifera oil, characterized by TAG depletion, DAG enrichment, and low MAG levels. Docking and 120-ns MD simulations indicated that SHSL accommodated oleoyl-rich TAG in a more favorable catalytic geometry than downstream DAG and MAG substrates, involving Ser150 proximity and oxyanion-hole stabilization. These results provide a structural interpretation for TAG-to-DAG-biased redistribution and support SHSL as a candidate biocatalyst for enzymatic modification of C. oleifera oil. Download: Download high-res image (212KB) Download: Download full-size image